rental apartment in the outer area

hello,
i am new here and hope that a few experts can give me some tips.
now to the current question. we have always lived in the outskirts. our parents did too, long ago. about 15 years ago we received a building permit for an extension. since then, our house has contained two separate apartments. the smaller one was occupied by our parents until some time ago. the other by us. since the parents have now passed away, we are considering what to do with the vacant apartment. we do not need it ourselves. therefore, we would like to rent it out, but we have now read in the building permit from back then that the house may only be occupied by the owner and close relatives...

what can we do? is it really the case that in times of housing shortage (there is almost weekly news about this in the newspapers) we are not allowed to rent out this apartment? do we have to leave the apartment empty and let it decay??? what options are there? who has advice for us???

You only need to submit an application to change the use. Whether you will be successful with it remains uncertain. [Außenbereich] basically means: no living space, but recreational areas, agriculture, etc. The infrastructure in [Außenbereich] is not like in [Innenbereich]. Municipalities usually want to protect themselves from having too large settlements in [Außenbereich], so that school buses, kindergartens, etc. are not suddenly needed there. Therefore, they often try to direct residential concentration to the [Innenbereich]. The [Innenbereich] must be expanded and enlarged as you so nicely put it, in order to combat the housing shortage. The [Außenbereich] (no / few buses, no schools, no kindergartens, etc.) in my view should also continue not to be significantly designated for housing. What unfortunately keeps happening: people move into the [Außenbereich] and then make demands such as connection to the public sewer system, road renovations, etc. Municipalities want to protect themselves from such things.